wip: echo

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "extern/Unity"]
+	path = extern/Unity
+	url = https://github.com/ThrowTheSwitch/Unity.git

.vscode/settings.json

@@ -1,4 +0,0 @@
-{
-    "editor.defaultFormatter": "ms-vscode.cpptools",
-    "editor.formatOnSave": true
-}

examples/cp/.gitignore

@@ -1 +1,3 @@
-cp_priv_sep
+c
+c_cgroup
+ml

examples/cp/Makefile

@@ -1,17 +1,13 @@
 C=clang
 
-all: c cp_priv_sep c_cgroup ml
+all: c c_cgroup ml
 
 clean:
-	rm -f c cp_priv_sep c_cgroup ml
+	rm -f c ml
 
 c: cp.c
 	${C} -o c cp.c
 
-cp_priv_sep: cp_priv_sep.c ../../lib/clone3.c ../../include/clone3.h
-	${C} -I../../include -o cp_priv_sep cp_priv_sep.c ../../lib/clone3.c
-	sudo setcap CAP_SYS_ADMIN+eip ./cp_priv_sep
-
 c_cgroup: cp_cgroup.c
 	${C} -o c_cgroup cp_cgroup.c
 

examples/cp/cp_cgroup.c

@@ -31,7 +31,37 @@ off_t get_file_size(int fd) {
 /*
  * Move self to a leaf node of the cgroup.
  */
-int leaf_self() {}
+int leaf_self() {
+  int cgroup_fd = open("/proc/self/cgroup", O_RDONLY);
+  if (cgroup_fd == -1) {
+    perror("open");
+    return -1;
+  }
+
+  if (lseek(cgroup_fd, 3, SEEK_SET) == -1) {
+    perror("lseek");
+    return -1;
+  }
+
+  char cgroup_root_dir[1024] = "/sys/fs/cgroup";
+
+  off_t len;
+  if ((len = read(cgroup_fd, cgroup_root_dir + 14, 1010)) == -1) {
+    perror("read");
+    return -1;
+  }
+  cgroup_root_dir[len + 17] = 0x00;
+
+  fprintf(stderr, "%s\n", cgroup_root_dir);
+
+  int cgroup_dd = open(cgroup_root_dir, O_DIRECTORY);
+  if (cgroup_dd == -1) {
+    perror("open");
+    return -1;
+  }
+
+  return 0;
+}
 
 /*
  * Perform the copy between the two file descriptors.
@@ -112,6 +142,8 @@ int main(int argc, char **argv) {
   }
 
   // setup a cgroup for the child
+  if (leaf_self() == -1)
+    return -1;
 
   // wait for the child to pause and restart it
   int status;

examples/cp/cp_priv_sep.c

@@ -1,154 +0,0 @@
-// For privilege separation
-#include <clone3.h>
-#include <fcntl.h>
-#include <linux/wait.h>
-#include <stdint.h>
-#include <stdlib.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <unistd.h>
-
-// This program
-#include <stdio.h>
-
-#define BUF_SIZE 4096
-
-struct copy_args {
-  char *src;
-  char *dst;
-};
-
-int process_args(int argc, char **argv, struct copy_args *);
-int do_copy(struct copy_args *args);
-
-int main(int argc, char **argv) {
-  pid_t child;
-
-  // Spawn args processor
-  int args_pid_fd;
-
-  struct clone_args args_processor_cl_args = {
-      .flags = CLONE_NEWIPC | CLONE_NEWNET | CLONE_NEWNS | CLONE_NEWPID |
-               CLONE_NEWUSER | CLONE_NEWUTS | CLONE_PIDFD,
-      .pidfd = (uint64_t)&args_pid_fd,
-      .child_tid = (uint64_t)NULL,
-      .parent_tid = (uint64_t)NULL,
-      .exit_signal = SIGCHLD,
-      .stack = (uint64_t)NULL,
-      .stack_size = 0,
-      .tls = (uint64_t)NULL,
-  };
-
-  int args_pipe_fds[2];
-  if (pipe(args_pipe_fds) < 0) {
-    perror("pipe");
-    exit(-1);
-  }
-
-  if ((child = clone3(&args_processor_cl_args)) == 0) {
-    char args[sizeof(struct copy_args)];
-
-    int code = process_args(argc, argv, &args);
-    if (code != 0) {
-      exit(code);
-    }
-
-    write(args_pipe_fds[1], &args, sizeof(args));
-    exit(0);
-  } else if (child < 0) {
-    perror("clone3");
-    return -1;
-  }
-
-  // Wait for args processor
-  // Implicit assertion that sizeof(args) < the pipe buffer size (won't block)
-  siginfo_t status;
-  if (waitid(P_PIDFD, args_pid_fd, &status, WEXITED) == -1) {
-    perror("waitid");
-    return -1;
-  }
-
-  if (status.si_status != 0) {
-    return status.si_status;
-  }
-
-  char args[sizeof(struct copy_args)];
-  read(args_pipe_fds[0], &args, sizeof(args));
-
-  // Spawn copier (can be more separated)
-  int copy_pid_fd;
-
-  struct clone_args do_copy_cl_args = {
-      .flags = CLONE_NEWIPC | CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWUTS |
-               CLONE_PIDFD,
-      .pidfd = (uint64_t)&copy_pid_fd,
-      .child_tid = (uint64_t)NULL,
-      .parent_tid = (uint64_t)NULL,
-      .exit_signal = SIGCHLD,
-      .stack = (uint64_t)NULL,
-      .stack_size = 0,
-      .tls = (uint64_t)NULL,
-  };
-
-  if ((child = clone3(&do_copy_cl_args)) == 0) {
-    int code = do_copy(&args);
-    exit(code);
-  } else if (child < 0) {
-    perror("clone3");
-    return -1;
-  }
-
-  if (waitid(P_PIDFD, copy_pid_fd, &status, WEXITED) == -1) {
-    perror("waitid");
-    return -1;
-  }
-
-  return status.si_status;
-}
-
-int process_args(int argc, char **argv, struct copy_args *args) {
-  if (argc != 3) {
-    fprintf(stderr, "usage: %s SRC DST\n", argv[0]);
-    return -1;
-  }
-
-  args->src = argv[1];
-  args->dst = argv[2];
-
-  return 0;
-}
-
-int do_copy(struct copy_args *args) {
-  fprintf(stderr, "src: `%s`; dst: `%s`\n", args->src, args->dst);
-  int src_fd, dst_fd;
-
-  if ((src_fd = open(args->src, O_RDONLY)) < 0) {
-    perror("open");
-    return 1;
-  }
-  if ((dst_fd = open(args->dst, O_WRONLY | O_CREAT | O_TRUNC)) < 0) {
-    perror("open");
-    return 1;
-  }
-
-  char buf[BUF_SIZE];
-  while (1) {
-    int read_bytes = read(src_fd, buf, BUF_SIZE);
-    if (read_bytes < 0) {
-      perror("read");
-      return read_bytes;
-    }
-
-    if (!read_bytes) {
-      fprintf(stderr, "copy complete\n");
-      return 0;
-    }
-
-    if (write(dst_fd, buf, read_bytes) < 0) {
-      perror("write");
-      return -1;
-    }
-  }
-
-  return 0;
-}

examples/echo/.gitignore

@@ -1 +0,0 @@
-echo_priv_sep

examples/echo/Makefile

@@ -1,10 +0,0 @@
-C=clang -Wall
-
-all: echo_priv_sep
-
-clean:
-	rm -f echo_priv_sep
-
-echo_priv_sep: echo_priv_sep.c ../../lib/clone3.c ../../include/clone3.h
-	${C} -I../../include -o echo_priv_sep echo_priv_sep.c ../../lib/clone3.c
-	sudo setcap CAP_SYS_ADMIN+eip ./echo_priv_sep

examples/echo/echo_priv_sep.c

@@ -1,196 +0,0 @@
-// For privilege separation
-#include <clone3.h>
-
-#include <linux/wait.h>
-#include <stdlib.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <unistd.h>
-
-// This program
-#include <netinet/in.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <sys/socket.h>
-#include <sys/types.h>
-
-#define BUF_SIZE 1024
-
-int real_main(int, char **, int);
-int request_handler(int);
-
-int main(int argc, char **argv) {
-  pid_t child;
-
-  int num_pids = 2;
-  int pid_fds[num_pids];
-
-  // Create IPC
-  int pipe_fds[2];
-  if (pipe(pipe_fds) < 0) {
-    perror("pipe");
-    exit(-1);
-  }
-
-  // Spawn real_main
-  // Use CLONE_FILES to have the opened fds passed up
-  struct clone_args real_main_cl_args = {
-      .flags = CLONE_NEWIPC | CLONE_NEWNS | CLONE_NEWPID | CLONE_NEWUSER |
-               CLONE_NEWUTS | CLONE_PIDFD | CLONE_FILES,
-      .pidfd = (uint64_t)&pid_fds[0],
-      .child_tid = (uint64_t)NULL,
-      .parent_tid = (uint64_t)NULL,
-      .exit_signal = SIGCHLD,
-      .stack = (uint64_t)NULL,
-      .stack_size = 0,
-      .tls = (uint64_t)NULL,
-  };
-
-  if ((child = clone3(&real_main_cl_args)) == 0) {
-    int code = real_main(argc, argv, pipe_fds[1]);
-    exit(code);
-  } else if (child < 0) {
-    perror("clone3");
-    exit(-1);
-  }
-
-  // Spawn internal cloner (to maintain capabilities)
-  // Use CLONE_FILES to pass the opened fds down
-  struct clone_args process_generator_cl_args = {
-      .flags = CLONE_FILES,
-      .pidfd = (uint64_t)&pid_fds[1],
-      .child_tid = (uint64_t)NULL,
-      .parent_tid = (uint64_t)NULL,
-      .exit_signal = SIGCHLD,
-      .stack = (uint64_t)NULL,
-      .stack_size = 0,
-      .tls = (uint64_t)NULL,
-  };
-
-  if ((child = clone3(&process_generator_cl_args)) == 0) {
-    int read_pipe = pipe_fds[0];
-
-    int client_fd;
-    while (1) {
-      int bytes_read = read(read_pipe, &client_fd, sizeof(client_fd));
-      if (bytes_read == 0) {
-        break;
-      } else if (bytes_read < 0) {
-        perror("read");
-        exit(-1);
-      }
-
-      fprintf(stderr, "got client_fd: %d\n", client_fd);
-
-      // Do not use CLONE_FILES for default CoW behaviour
-      struct clone_args request_cl_args = {
-          .flags = CLONE_NEWIPC | CLONE_NEWNS | CLONE_NEWPID | CLONE_NEWUSER |
-                   CLONE_NEWUTS | CLONE_PIDFD,
-          .pidfd = (uint64_t)&pid_fds[0],
-          .child_tid = (uint64_t)NULL,
-          .parent_tid = (uint64_t)NULL,
-          .exit_signal = SIGCHLD,
-          .stack = (uint64_t)NULL,
-          .stack_size = 0,
-          .tls = (uint64_t)NULL,
-      };
-
-      if ((child = clone3(&request_cl_args)) == 0) {
-        int code = request_handler(client_fd);
-        exit(code);
-      } else if (child < 0) {
-        perror("clone3");
-        exit(-1);
-      }
-    }
-
-    exit(0);
-  } else if (child < 0) {
-    perror("clone3");
-    exit(-1);
-  }
-
-  // Wait for child processes
-  siginfo_t status;
-
-  for (int i = 0; i < num_pids; i++) {
-    if (waitid(P_PIDFD, pid_fds[i], &status, WEXITED) == -1) {
-      perror("waitid");
-      return -1;
-    }
-    if (status.si_status != 0) {
-      return status.si_status;
-    }
-  }
-
-  return 0;
-}
-
-int real_main(int argc, char **argv, int write_pipe) {
-  if (argc != 2) {
-    fprintf(stderr, "expected 1 argument\n");
-    return -1;
-  }
-
-  int port = atoi(argv[1]);
-
-  int server_fd = socket(AF_INET, SOCK_STREAM, 0);
-  if (server_fd < 0) {
-    perror("socket");
-  }
-
-  int opt_val = 1;
-  setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &opt_val, sizeof opt_val);
-
-  struct sockaddr_in server;
-
-  server.sin_family = AF_INET;
-  server.sin_port = htons(port);
-  server.sin_addr.s_addr = htonl(INADDR_ANY);
-
-  if (bind(server_fd, (struct sockaddr *)&server, sizeof(server)) < 0) {
-    perror("bind");
-  }
-
-  if (listen(server_fd, 16) < 0) {
-    perror("listen");
-  }
-
-  while (1) {
-    struct sockaddr_in client;
-    socklen_t client_len = sizeof(client);
-
-    int client_fd = accept(server_fd, (struct sockaddr *)&client, &client_len);
-    if (client_fd < 0) {
-      perror("accept");
-    }
-
-    write(write_pipe, &client_fd, sizeof(client_fd));
-    fprintf(stderr, "sent client_fd: %d\n", client_fd);
-  }
-
-  return 0;
-}
-
-int request_handler(int client_fd) {
-  char buf[BUF_SIZE];
-  while (1) {
-    int read = recv(client_fd, buf, BUF_SIZE, 0);
-    if (read < 0) {
-      perror("recv");
-      return read;
-    }
-
-    if (!read) {
-      fprintf(stderr, "connection terminated\n");
-      return 0;
-    }
-
-    if (send(client_fd, buf, read, 0) < 0) {
-      perror("send");
-      return -1;
-    }
-  }
-
-  return 0;
-}

examples/fib/.gitignore

@@ -1 +0,0 @@
-fib_priv_sep

examples/fib/Makefile

@@ -1,10 +0,0 @@
-C=clang -Wall
-
-all: fib_priv_sep
-
-clean:
-	rm -f fib_priv_sep
-
-fib_priv_sep: fib_priv_sep.c ../../lib/clone3.c ../../include/clone3.h
-	${C} -I../../include -o fib_priv_sep fib_priv_sep.c ../../lib/clone3.c
-	sudo setcap CAP_SYS_ADMIN+eip ./fib_priv_sep

examples/fib/fib_priv_sep.c

@@ -1,76 +0,0 @@
-// For privilege separation
-#include <clone3.h>
-
-#include <linux/wait.h>
-#include <stdlib.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-
-// This program
-#include <stdint.h>
-#include <stdio.h>
-
-uint64_t fib(uint64_t i) {
-  uint64_t a = 0;
-  uint64_t b = 1;
-
-  for (; i > 0; i--) {
-    uint64_t old_b = b;
-    b = b + a;
-    a = old_b;
-  }
-
-  return a;
-}
-
-int real_main(int argc, char **argv);
-
-int main(int argc, char **argv) {
-  int pid_fd;
-
-  struct clone_args cl_args = {
-      .flags = CLONE_NEWIPC | CLONE_NEWNET | CLONE_NEWNS | CLONE_NEWPID |
-               CLONE_NEWUSER | CLONE_NEWUTS | CLONE_PIDFD,
-      .pidfd = (uint64_t)&pid_fd,
-      .child_tid = (uint64_t)NULL,
-      .parent_tid = (uint64_t)NULL,
-      .exit_signal = SIGCHLD,
-      .stack = (uint64_t)NULL,
-      .stack_size = 0,
-      .tls = (uint64_t)NULL,
-  };
-
-  pid_t child = clone3(&cl_args);
-  if (child < 0) {
-    perror("clone3");
-    exit(-1);
-  } else if (child == 0) {
-    int code = real_main(argc, argv);
-    exit(code);
-  } else {
-    siginfo_t status;
-    if (waitid(P_PIDFD, pid_fd, &status, WEXITED) == -1) {
-      perror("waitid");
-      return -1;
-    }
-
-    exit(status.si_status);
-  }
-}
-
-int real_main(int argc, char **argv) {
-  if (argc != 2) {
-    fprintf(stderr, "expected 1 argument\n");
-    return -1;
-  }
-
-  uint64_t i = 0;
-  if (sscanf(argv[1], "%lu", &i) != 1) {
-    fprintf(stderr, "sscanf failed\n");
-    return -1;
-  }
-
-  uint64_t fib_result = fib(i);
-  printf("fib(%lu) = %lu\n", i, fib_result);
-  return 0;
-}

examples/unshare_umount.c

@@ -1,15 +0,0 @@
-#define _GNU_SOURCE
-#include <sched.h>
-#include <sys/mount.h>
-#include <sys/types.h>
-#include <dirent.h>
-#include <stdio.h>
-
-int main() {
-	if (unshare(CLONE_NEWNS))
-		perror("unshare");
-	if (mount("none", "/", NULL, MS_REC|MS_PRIVATE, NULL))
-		perror("mount");
-	if (umount("/"))
-		perror("umount");
-}

extern/Unity

@@ -0,0 +1 @@
+Subproject commit 8ba01386008196a92ef4fdbdb0b00f2434c79563

include/clone3.h

@@ -1,3 +0,0 @@
-#include <linux/sched.h>
-
-long clone3(struct clone_args *cl_args);

lib/clone3.c

@@ -1,7 +0,0 @@
-#include <clone3.h>
-#include <sys/syscall.h>
-#include <unistd.h>
-
-long clone3(struct clone_args *cl_args) {
-  return syscall(SYS_clone3, cl_args, sizeof(struct clone_args));
-}